In vehicle headlight assemblies, it is necessary to ensure that the lamp is correctly aimed so that it provides adequate illumination of the road without dazzling drivers of oncoming vehicles. For this purpose, it is necessary to mount the reflector body of the headlight assembly relative to a support in such a way that it can be adjusted by independent tilting movement about horizontal and vertical axes. It is common practice to mount the reflector body on the support through three pivotal connections each having a limited amount of universal pivotal movement. An adjusting screw is connected with each of two of the three pivotal connections so that each screw can be moved independently. The pivotal connections and adjusting screws are so arranged that rotation of one of the screws causes the headlamp to be tilted about a horizontal axis whilst rotation of the other screw causes tilting movement of the headlamp about a vertical axis. However, each adjusting screw moves linearly whilst the lamp body tilts about the respective pivot axis. The result of this is that a strain is applied which may be sufficiently severe to distort the reflector body sufficiently to affect the light beam performance.